Front-engine Rear-drive (FR) vehicles should have a propeller shaft for transmitting the driving force of the engine to the rear differential. The propeller shaft is generally equipped at the center of the vehicle with a center bearing that is supported by a center portion of the center floor panel of the vehicle body.
Therefore, the mounting portion structure of the center bearing at the center floor panel and the adjacent portions thereof should be designed to have sufficient rigidity to withstand vibration or exciting force (giving rise to the vibration) that can be transmitted from the propeller shaft to the vehicle body.